Hi Everyone. New member here - and not a mechanic. I have recently purchased a 2011 motorhome on a Fiat Ducato chassis - 2.3 MJD, with 23,000 miles. I noticed a 'buzzing' from the centre of the dashboard and traced the noise to the EGR control valve. My local garage confirmed that this was where the noise was coming from and said they could replace the EGR CV but that the noise could come back... Well as it was an expensive item and since the van is under warranty, I decided to have it changed. It was fine for a short while but now after just a couple of hundred miles, the noise is back. I have read that this can also be because of a problem with the throttle body. Just want to try and point my local garage in the right direction with this and try and get the problem fixed while I'm still in warranty from the dealer I bought it from. Thanks!
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Technical Noisy EGR Control Valve
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Hi oldgustav. I can't help with determining if your control valve is excessively noisy, but it might help you to know my understanding of how the setup works.
The EGR control valve sits at the top centre of the engine bay on a bracket. It is supplied with a rapid on/off electrical signal from the ECU, which causes its internal valve to move a small amount. This allows through a greater or lesser amount of vacuum as required. The variable vacuum is then applied to the EGR valve itself, to move its internal flap and thus vary the amount of exhaust gas recirculated into the inlet manifold for emission control purposes. The vacuum input and ouput lines are thin rubber hoses. The rapid on/off signal causes a certain amount of buzzing noise from the control valve, which is more noticable during the run-on phase for a minute or so just after the engine has been stopped. I can't remember whether the valve has rubber mounts to reduce the buzzing vibration transmitted into the bulkhead. If it does, check they haven't gone hard or perished. I assume that the EGR valve would need too much effort or be too hot to simply move directly from an electrical solenoid, hence the two-stage arrangement.
The throttle valve controls the amount of air admitted to the engine, again for emission control purposes. Less air supply encourages more exhaust gas to be recirculated. It has a lightweight sprung flap whose position is directly controlled by an electric actuator. It sometimes gets confused with the EGR valve proper.
The EGR control valve sits at the top centre of the engine bay on a bracket. It is supplied with a rapid on/off electrical signal from the ECU, which causes its internal valve to move a small amount. This allows through a greater or lesser amount of vacuum as required. The variable vacuum is then applied to the EGR valve itself, to move its internal flap and thus vary the amount of exhaust gas recirculated into the inlet manifold for emission control purposes. The vacuum input and ouput lines are thin rubber hoses. The rapid on/off signal causes a certain amount of buzzing noise from the control valve, which is more noticable during the run-on phase for a minute or so just after the engine has been stopped. I can't remember whether the valve has rubber mounts to reduce the buzzing vibration transmitted into the bulkhead. If it does, check they haven't gone hard or perished. I assume that the EGR valve would need too much effort or be too hot to simply move directly from an electrical solenoid, hence the two-stage arrangement.
The throttle valve controls the amount of air admitted to the engine, again for emission control purposes. Less air supply encourages more exhaust gas to be recirculated. It has a lightweight sprung flap whose position is directly controlled by an electric actuator. It sometimes gets confused with the EGR valve proper.
Hi Anthony489. Thanks for the explanation of how the EGR works. I will certainly go and have a look at the rubber mounts but my guess is that if they were faulty they would have been changed when the EGR was replaced last week. The 'buzz' is excessive, so I can't think that it's right. I'd read on a MH forum that problems with EGR have been traced back to the throttle body. EGR is a 5 minute job to change. Not so the throttle body...
Dennis Egestad
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theoneandonly
Established member
@Dennis Egestad I'm just repeating yor post as it was hidden amongst other things. Sorry I have no experience of your motor but others have and may be able to help. @Anthony489 @LandyAndy
Dennis from Denmark.Hi, did you ever find out why the buzzing noise came back? Was it an original Fiat EGR valve that was put on or a non original? I have a similar model and experienced the same irritating noise and replaced the EGR valve with a non original and it was silent for 600 kilometers. Then the noise came back and it sounded even more worse than the old one. Replaced it once more with a second non original (another brand) and the same thing happened - the noise came back after 300 kilometers. Has anyone experienced that? I am thinking of replacing it this time with an original Fiat spare part but would love some feedback if others have experienced the same problem? Thanks.
Dennis from Denmark.Hi, did you ever find out why the buzzing noise came back? Was it an original Fiat EGR valve that was put on or a non original? I have a similar model and experienced the same irritating noise and replaced the EGR valve with a non original and it was silent for 600 kilometers. Then the noise came back and it sounded even more worse than the old one. Replaced it once more with a second non original (another brand) and the same thing happened - the noise came back after 300 kilometers. Has anyone experienced that? I am thinking of replacing it this time with an original Fiat spare part but would love some feedback if others have experienced the same problem? Thanks.
Crossingkeeper
Established member
This is by way of being a 'non-reply' to your query but, on the basis all info is useful, here goes.....
When I first intermittently had the P0638 code I replaced the original solenoid valve with a non OE one (£45 from ebay!) on the basis it might be an easy cheap fix. It wasn't and I eventually had to have the throttle body replaced which was an expensive fix!
I've left the replacement solenoid valve in place and it has not started to buzz after a couple of thousand miles; however the original one didn't buzz either (hence this being a non-reply!)
Is it possible that another issue in your system is overworking the solenoid valve?
When I first intermittently had the P0638 code I replaced the original solenoid valve with a non OE one (£45 from ebay!) on the basis it might be an easy cheap fix. It wasn't and I eventually had to have the throttle body replaced which was an expensive fix!
I've left the replacement solenoid valve in place and it has not started to buzz after a couple of thousand miles; however the original one didn't buzz either (hence this being a non-reply!)
Is it possible that another issue in your system is overworking the solenoid valve?
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Hi Denis
Did you check the rubber anti-vibration mounts ?
Did you check the rubber anti-vibration mounts ?